This invention relates to apparatus and methods for testing the optical signal quality of an optical fibre, for example in a telecommunications optical drop cable before it is connected to subscriber apparatus.
Fiber monitoring methods today are well established to allow for testing of a fiber optic link. This can be done using various kinds of optical time domain reflectometer set-ups (OTDR) and this has been widely adopted in checking the quality of long distance fiber links. For FTTH (fiber to the home) deployments, however, there is a growing need for low-cost monitoring methods to check the quality of a short distance link in a highly branched network. More specifically, a low cost method is still lacking for checking the quality of drop cable deployment, i.e. a predefined connected cable that is laid by a first installation crew from a terminal up to a certain point that is not yet connected to the optical network terminal (ONT). The drop point will most likely be a multi-dwelling unit (MDU) e.g. an apartment building, where generally a group of ONT's is located, but single or other subscriber connection boxes are not excluded. Upon subscriber demand for a connection, a second crew must visit to make the connection from the ONT in the subscriber's residence to the drop cable in the MDU. Ideally, a check for correct installation of the drop cable should be available to the subscriber connection crew to confirm that the drop cable link is still free of faults before starting to connect the subscriber, especially in an MDU.